Improvement in machining accuracy of micro-dimples fabricated in a sandwich-like electrochemical micromachining unit using a porous cathode

Abstract

Surface texture plays a significant role in improving interfacial performance of mechanical components. Electrochemical micromachining is a feasible method for preparing micro-dimples. Sandwich-like electrochemical micromachining (SLEMM) could be used for generating micro-dimples, in which the cathodic tool keeps in close contact with the mask firmly laminated to the anodic workpiece surface, and the dissolution of the workpiece takes place in the enclosed unit. The shallow micro-dimples could be machined with the electrolytic products accumulating on the workpiece surface in the enclosed unit of SLEMM. A porous metal cathode was employed in SLEMM resulting in an open unit, which could remove electrolytic products and generate deep micro-dimples. However, there is poor machining accuracy of micro-dimples obtained with stationary electrolyte over the porous cathode. Pulse electrochemical micromachining is an effective method for enhancing the machining accuracy of micro-dimples. Therefore, the pulse is applied to improve the machining accuracy of micro-dimples generated in SLEMM with a porous metal cathode. And the different electrolyte flow modes over the porous metal cathode are employed to investigate their influence on machining accuracy of micro-dimples. The experimental results indicate that the pulse current power supply could improve the machining accuracy of micro-dimples, compared with direct current power supply. Furthermore, the machining accuracy of micro-dimples could be improved by lateral flow mode, compared with radial flow mode. With a 40% pulse duty ratio, 4 kHz pulse frequency, 15 V applied voltage, and 6 s effective machining time, the micro-dimples have a good machining accuracy on multiple anodic workpieces.